Potential of Induction Inline-melting Technology of Mineral Raw Materials in Recycling of Dusty, Powdery and Sludge Waste


Authors: Katharina Grass, Victor Bartashov

IB Engineering GmbH, Vienna, Austria





Introduction: Target Setting and Possible Solutions


Companies of different industries face the same issues while recycling dusty, powdery and sludge waste:

·         high costs for transport and landfilling,

·         strict environmental standards for waste disposal and, as a result, a failure to dispose of waste in its original form,

·         loss of profit from metals recovered from waste.

Such industries are, among others:

·         recycling of zinc-containing filter dust from the steel industry,

·         recycling of lithium-ion batteries,

·         recycling of sludge from municipal sewage treatment plants,

·         recycling of fly ash from waste incineration plants.

The list could be continued.

In some cases, the solution comes with reducing of waste volume and compliance with environmental standards for disposal. In other cases, there is also a possibility of making additional profit by recovering valuable metals.


1.      Vitrification / Waste Inertization (IBEwi)


In cases where the recovery of certain metals is not economically justified, but strict environmental requirements apply, the waste can be converted into an optimal product for disposal by vitrification.

Vitrification / Inertization is a method of immobilizing оf toxic substances (such as heavy metals) by enclosing them in a stable matrix (e.g. in a silicate matrix). Vitrification prevents harmful components from leaching out over time.

Consider an example of the immobilization of toxic substances through vitrification of fly ash from waste incineration. When waste is burned in incinerators, fly ash containing a large amount of dangerous chemical compounds, including heavy metals, emerges. Some heavy metals are volatile at higher temperatures (e.g. Hg, Cd, Pb). Due to their volatility, these metals accumulate on fly ash in the form of water-soluble salts. Landfilling of these ashes without pre-treatment would lead to soil and groundwater contamination. A widely used method of cementing fly ash before disposal reduces the immediate release of heavy metals and other toxic substances into the soil but does not completely prevent it. These substances enter the environment through gradual leaching. In the long run, cement is not a reliable material for binding dangerous chemicals and heavy metals. Vitrification is not only a reliable method to prevent toxic substances from leaching out, but also allows to significantly (!) reduce the volume of waste. As a result, the waste requires significantly less landfill space. The costs of landfill disposal are reduced accordingly.

The vitrification process IBEwi patented by our company takes place in the following sequence (example of fly ash):

The fly ash is first melted in an IBE inline induction melting furnace. Melting is possible both in pure form and with the addition of glass-forming components such as sand, sodium, etc. The melt leaking from the opening of melting furnace undergoes dry granulation. The resulting vitrified product (granulate) is chemically stable and prevents a leaching of heavy metals.

Obtaining a glassy product (granulate) in some cases is economically justified even for the purpose of reducing the waste volume. An example hereof are companies that continuously use mineral wool products but not produce mineral wool themselves (e.g. use of mineral wool for hydroponic systems). After processing mineral wool waste to granules, its volume is reduced by 100 times, which significantly lessens disposal costs.


2.      Recovery of Metals

2.1. When Is It Profitable?


Theoretically, the recovery of metals is possible in most cases of disposal of metal-containing dusty waste. For example, it is basically possible to separate metals from fly ash during waste incineration (see above), but the criterion for such an operation is the expediency and profitability of this process. In this case, the production of metals from fly ash is uneconomical due to different, constantly changing composition of the burnt waste.

With a known composition of waste, the process of obtaining metals from waste can be beneficial, if the prices for the resulting chemical element are high enough. Many chemical elements are found in nature in limited quantities. Thus, their prices, even with stable demand, will continue to grow in the future. An increase in prices is also possible with an increasing demand for a particular raw material in connection with the development of a particular industrial sector. Thus, nickel prices are increasing due to the growing demand for this metal on the part of manufacturers of lithium-ion batteries [1].



Fig. 1: Demand for nickel, t / year

Source: Buchert M., Sutter J.: Stand und Perspektiven des Recyclings von Lithium-Ionen-Batterien aus der Elektromobilität. (Current status and prospects for recycling lithium-ion batteries from electric vehicles)

Similar trends are observed with lithium and cobalt. The graphs show the projected demand for cobalt and lithium feedstocks through 2050.



Fig. 2: Demand for cobalt, t / year

Source: Buchert M., Sutter J.: Stand und Perspektiven des Recyclings von Lithium-Ionen-Batterien aus der Elektromobilität. (Current status and prospects for recycling lithium-ion batteries from electric vehicles)



Fig. 3: Demand for lithium, t / year

Source: Buchert M., Sutter J.: Stand und Perspektiven des Recyclings von Lithium-Ionen-Batterien aus der Elektromobilität. (Current status and prospects for recycling lithium-ion batteries from electric vehicles)


Another valuable metal, the price of which has recently been steadily growing, is zinc. In 2020, zinc reserves fell to their lowest level in the last 11 years. Back in 2013, the reserves of this metal at the LME[1] reached 1.2 million t; gradually decreasing, they reached 256 thousand t in the 1st quarter of 2021 [2].


2.2. Metal Recovery Process of Company IB Engineering (IBEmr)


The principle behind all IBE metal recovery technologies is basically the same and includes:

·         high-temperature smelting of waste in an IBE inline induction melting furnace,

·         separation of the liquid metal phase from the phase of mineral melt,

·         evaporation of metals, followed by rapid cooling, condensation and product collecting in filters (Fig. 4).


1. mineral meltà slag    2. liquid metal phase  3. metal-containing filtrate.


Fig. 4: IBEmr: IBE technology used for metal recovery from metal-containing waste

Slag can be used, for example, in road construction, and profit could be made from obtained metals.


2.3. Examples of Metal Recovery from Industrial Waste


Some examples of applications, where valuable metals can be recovered from dusty and powdery industrial waste, are given below.


Utilization of zinc-containing filter dust of metallurgical plants

Around 30% of global steel production were achieved by melting steel scrap in an electric arc furnace (EAF). For every ton of molten scrap, 15 to 22 kg of dust is generated, which is collected in filters. This means that about 8.5 million tons of filter dust are produced annually, containing 1.7 million t of zinc. Only around 45% of this dust worldwide are recycled, and the rest is deposited in landfills. [3]

Currently, one of the most common methods of recovering zinc from metallurgical EAF dust is the Waelz process (method of recovering zinc from EAF dust in a rotary kiln). The disadvantages of the Waelz process are: pelletizing with consumption of slag formers, high fuel consumption, difficulties with temperature control; the Zn content in the dust must be at least 20%; iron and up to 5% zinc are lost with slag.

IB Engineering offers an innovative technological solution that corresponds to the above principle (Fig. 4):

Firstly, the metallurgical filter dust is heated in an IBE induction melting furnace with the addition of a reducing agent (e. g. carbon, in the form of broken coke). The reduced zinc vapor (at oven temperature >950°C) is passing through the oxidation zone and cooling zone and is collected as oxide in the filter. The slag is collected in a container provided for this purpose and can be easily disposed of or used (e. g. in road construction).


Recycling of lithium-ion batteries

On the one hand, storage and disposal of used lithium-ion electric vehicle batteries entail a high risk of environmental pollution and potential danger to human health due to the release of toxic elements and gases. On the other hand, lithium-ion batteries are a valuable resource, when properly recycled.  For example, a lithium-ion battery with a capacity of 50 kW*h, suitable for a range of 250 to 300 km, contains about 10 kg of manganese, 11 kg of cobalt, 32 kg of nickel and slightly more than 6 kg of lithium [4].

Currently, recycling lithium batteries in order to recover valuable metals does not pay off for all the metals they contain. Lithium, for example, is not economically recyclable. It is possible to extract it from old lithium-ion batteries to save raw materials, but today it is uneconomical [5]. According to experts' forecasts, the demand for lithium will increase in the near future, and by 2050 it will already amount to more than 1,000,000 t/y (Fig. 3). This is primarily due to an increase in the future production of electric vehicles.

The principle of the process is shown in the diagram (Fig. 4) and described above. It is also applicable to the recycling of lithium-ion vehicle batteries and the separation of valuable metals from them. In this case, the preliminary stages of discharging, dismantling, mechanical crushing and fraction separation take place before pyrometallurgical methods are used.


3.      Potential of Inline Induction Melting in Recycling of Pulverized and Powdery Waste


Summarizing the above examples, it should be noted that one of the important components of the IBE technological cycle is induction melting. This applies to both the vitrification of waste and to more complex process of recovering valuable metals from waste.

Melting of waste in the IBE technological cycle takes place in a specially designed and patented induction furnace.

The benefits of melting in an IBE inline induction furnace:

·         working temperature up to 2500°С,

·         inline process, i.e. continuous movement of charge through tunnel from the starting material to the finished product,

·         the ability to melt a wide range of material fractions from 0 to 10 mm,

·         the possibility of obtaining three phases: two liquid phases (metallic and silicate mineral phase) and a gaseous phase, which, being condensed, is captured in filters.

In addition, the IBE Inline induction furnace demonstrates the following characteristics and potentials:

·         efficiency >90%,

·         uniformity of the melt temperature,

·         flexibility (quick power on/off),

·         full automation of the melting process; temperature control,

·         high safety and comfortable working conditions for staff,

·         absence of CO2 emissions.

For more information, please visit our website https://www.ibe.at/en/  or contact us directly.



[1] https://www.metalinfo.ru/ru/news/122016

[2] https://www.metalinfo.ru/ru/news/126391

[3] Curtis S.: Sustainability in Action: Recovery of Zink from EAF Dust in the Steel Industry, 2015 Intergalva Conference, Liverpool, England, 9th June 2015, http://www.icz.org.br/upfiles/arquivos/apresentacoes/intergalva-2015/5-2-Stewart.pdf

[4] https://www.jubatec.eu/recycling-von-lithium-ionen-akkus/ 

[5] https://futurezone.at/science/so-aufwendig-werden-alte-lithium-ionen-akkus-recycelt/401131764

[6] https://nachrichten.idw-online.de/2019/03/29/neues-verfahren-zur-zerstoerungsfreien-rueckgewinnung-von-kathodenmaterial-aus-lithium-ionen-batterien/


[1] LME: The London Metal Exchange